I don't waste time with bedding. I use loctite molly paste on the receiver, barrel extension and threads. If you torque the barrel nut appropriately, the receiver/barrel extension becomes one solid unit. The lapping tool is a marketing gimmick.
2 месяца назад
I think the lapping would have more validity if you knew the barrel flange mating surface was also true, not sure how you could true it or check it with that alignment pin present
My last upper assembly I got another bcm blem stripped upper and a fn 16" chrome lines barrel. The git was so tight I had to use heat as I usually do with the bcm uppers but this time it was even tighter so I had to use a clamp then barrel nut to pull it the remaining way into the upper. I will typically use loctite green 620 if it's loose but ever since swapping all my uppers to bcm there hasn't been a need as they mill the upper slightly undersize.
So much conflicting information out there about installing a barrel. I heard/read all sort of stuff; use Aero-Shell ant-seize grease, never use loctite you’ll never get it out again. Never shim the barrel to the upper, chemical reaction with the different metals may cause a fire, too tight a fit and the upper will crack and the gun will blow up on you. Don’t drive the barrel into the upper, by striking the muzzle, it’ll cause the barrel to jam in the upper at an angle and you could knock the lands into the grooves or knock its crown off. Also, you installed the barrel nut wrong, that clamp shell thing is for holding the upper and not a replacement for an action rod (are we going fishing?). Don’t over torque, don’t under torque the nut somewhere between thirty and sixty pounds is good. No shims, except between the barrel and nut and only if you can’t get that gas tube to slide just right through a notch in the nut and be perfectly straight. One of the most critical operations of putting one together, thanks for the fine job and detail.
" Never shim the barrel to the upper, chemical reaction with the different metals may cause a fire, too tight a fit and the upper will crack and the gun will blow up on you." You overstate several things here, I'll give you credit and suppose you're being funny. "Cause a fire," no, not just from using a shim. Not even close. Do you mean galvanic corrosion? Possible but mitgated with anti-seize of the appropriate compound/formula. "Too tight a fit and the upper will crack"? No, unless you don't know how to work on metallic things using tolerance fits, and don't know how to properly support each piece being worked. In other words, if you're not mechanically adept you can cause all kinds of problems. But shim stock doesn't cause fires and improving your extension/throat fit doesn't risk explosion or anything else. I suggest you, @sixoffive, avoid using all sharp objects. For your own safety.
@@seanoneil277 Yes, all good and fine observations and recommendations. Gotta be careful lost of misinformation on the inter web with all those commie bots everywhere. However, I cannot comply to your recommendations. You see, I enjoy a good run from time to time with scissors. I will try to think of you next time I do. Run with scissors.
All this is just a bunch of bs, started by these anal ( supposedly) gun builders. Do check the front of your receiver for burrs or whatnot, if it’s flat, slid your barrel in areo shell the threads and tightened your barrel nut down. I guarantee you, none of these gun manufacturers go through all that sh*t when they build their rifles. These people making a mountain out of a mole hill are redicioulas!!!!!
Pencil barrel? Has anyone tried lapping the barrel nut to the barrel flange? If the upper threads, nut threads, and nut clamping surface aren't coaxial, it will clamp unevenly, but I can't say I know that would matter.
Use a rubber band to keep the shim wrapped around the barrel extension while inserting the barrel. When the barrel is almost all the way in, cut the rubber band. When cutting the shim to size, do not use serrated scissors. Don't use green Loctite if you want to be able to easily remove the barrel. It's frick'n awful.
Blue loctite is not a retaining compound meant to fill gaps. Neither is green loctite (290). What you want to fill the gaps is one of the Loctite Retaining compounds, which are their 600 series. They just happen to be green. Not to be confused with green threadlocker.
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Use loctite 680 retaining compound w/ no shim. Never tap muzzle end, tap the back of the upper receiver.
Thanks gun dad. Very excited to start my first build and knowing how to properly prepare my parts gives me more confidence.
Why don't you just get an oversize barrel extension and the do a thermal fit?
This is gold. Thank you.
I don't waste time with bedding. I use loctite molly paste on the receiver, barrel extension and threads. If you torque the barrel nut appropriately, the receiver/barrel extension becomes one solid unit. The lapping tool is a marketing gimmick.
I think the lapping would have more validity if you knew the barrel flange mating surface was also true, not sure how you could true it or check it with that alignment pin present
No dust cover upper? Man after my own heart.
Loctite 620 bedding compound is what you want to use
My last upper assembly I got another bcm blem stripped upper and a fn 16" chrome lines barrel. The git was so tight I had to use heat as I usually do with the bcm uppers but this time it was even tighter so I had to use a clamp then barrel nut to pull it the remaining way into the upper. I will typically use loctite green 620 if it's loose but ever since swapping all my uppers to bcm there hasn't been a need as they mill the upper slightly undersize.
A geissele barrel nut works wonders for getting the barrel into the upper that last half of in inch instead of rubber mallet. Or after rubber mallet
Very nice results
So much conflicting information out there about installing a barrel. I heard/read all sort of stuff; use Aero-Shell ant-seize grease, never use loctite you’ll never get it out again. Never shim the barrel to the upper, chemical reaction with the different metals may cause a fire, too tight a fit and the upper will crack and the gun will blow up on you. Don’t drive the barrel into the upper, by striking the muzzle, it’ll cause the barrel to jam in the upper at an angle and you could knock the lands into the grooves or knock its crown off. Also, you installed the barrel nut wrong, that clamp shell thing is for holding the upper and not a replacement for an action rod (are we going fishing?). Don’t over torque, don’t under torque the nut somewhere between thirty and sixty pounds is good. No shims, except between the barrel and nut and only if you can’t get that gas tube to slide just right through a notch in the nut and be perfectly straight.
One of the most critical operations of putting one together, thanks for the fine job and detail.
" Never shim the barrel to the upper, chemical reaction with the different metals may cause a fire, too tight a fit and the upper will crack and the gun will blow up on you."
You overstate several things here, I'll give you credit and suppose you're being funny. "Cause a fire," no, not just from using a shim. Not even close. Do you mean galvanic corrosion? Possible but mitgated with anti-seize of the appropriate compound/formula.
"Too tight a fit and the upper will crack"?
No, unless you don't know how to work on metallic things using tolerance fits, and don't know how to properly support each piece being worked.
In other words, if you're not mechanically adept you can cause all kinds of problems. But shim stock doesn't cause fires and improving your extension/throat fit doesn't risk explosion or anything else.
I suggest you, @sixoffive, avoid using all sharp objects. For your own safety.
@@seanoneil277 Yes, all good and fine observations and recommendations. Gotta be careful lost of misinformation on the inter web with all those commie bots everywhere. However, I cannot comply to your recommendations. You see, I enjoy a good run from time to time with scissors. I will try to think of you next time I do. Run with scissors.
@@sixoffive 🤣
All this is just a bunch of bs, started by these anal ( supposedly) gun builders. Do check the front of your receiver for burrs or whatnot, if it’s flat, slid your barrel in areo shell the threads and tightened your barrel nut down. I guarantee you, none of these gun manufacturers go through all that sh*t when they build their rifles. These people making a mountain out of a mole hill are redicioulas!!!!!
What type of blue loctite you use? Thx for info!
Pencil barrel?
Has anyone tried lapping the barrel nut to the barrel flange? If the upper threads, nut threads, and nut clamping surface aren't coaxial, it will clamp unevenly, but I can't say I know that would matter.
Use a rubber band to keep the shim wrapped around the barrel extension while inserting the barrel. When the barrel is almost all the way in, cut the rubber band.
When cutting the shim to size, do not use serrated scissors.
Don't use green Loctite if you want to be able to easily remove the barrel. It's frick'n awful.
Blue loctite is not a retaining compound meant to fill gaps. Neither is green loctite (290).
What you want to fill the gaps is one of the Loctite Retaining compounds, which are their 600 series. They just happen to be green. Not to be confused with green threadlocker.